Warm mix asphalt: mechanical performance assessment and coating quality evaluation

Asphalt mix manufacturing requires heating and the drying of aggregates. The induced energy cost has opened the way to develop alternatives processes with low energy/ carbon materials such as Warm Mix (WMA). Their manufacturing requires specifics techniques to achieve similar performances to those of Hot Mix (HMA). However, the manufacturing temperature reduction can locally lead to imperfect bonding between bitumen and aggregates, although bonding quality measurement remains a challenge. This paper deals with mechanical performance of some mixes manufactured according to WMA processes in comparison to HMA. In addition, bitumen was extracted from the mixes and its rheological properties were studied. In a second step, the bonding quality was assessed by studying the heat fluxes exchanged between hot bitumen and warm aggregate in asphalt mix manufacturing conditions. This approach is based on the Thermal Contact Resistance (TCR) assessment at the binder / aggregate interface. The TCR reflects the contact imperfection at the microscopic scale when two materials are put into contact. This TCR was proposed as bonding quality indicator. Our studies showed that bonding quality depends on bitumen and aggregate temperatures during the contact. The higher the component’s temperatures, the lower the TCR values and better the bonding quality

Warm mix asphalt : Mechanical performances assessment and bonding quality measurement by thermal contact resistance

The classical asphalt mix manufacturing commonly requires the heating and the complete drying of aggregates. The induced energy cost has opened the way to develop alternatives processes with low energy/ carbon materials such as Warm Mix Asphalt (WMA). Their manufacturing requires specifics techniques to achieve similar performances than Hot Mix Asphalt (HMA). However, manufacturing temperature reduction can locally lead to incomplete aggregate coating by bitumen, although the coating quality measurement remains a challenge. This paper deals with modulus and fatigue performances of some bituminous mixtures manufactured at warm temperatures according to WMA processes in comparison with HMA. In addition, the binder has been extracted from asphalt and complex modulus has been studied. In a second step, an innovative thermal approach based on experimental and numerical method was studied. This approach is based on the Thermal Contact Resistance (TCR) assessment at the interface between the binder and the warm aggregate at the manufacturing step. This TCR is proposed as a coating quality indicator measurement. Our studies have shown that bonding quality depends on bitumen and aggregate temperatures during the contact. The higher the temperature, the lower the TCR and the better the bonding quality. Moreover, we found that TCR value is influenced by additives to modified bitumen properties

Méthode thermique d'évaluation de la qualité du collage bitume sur granulat par mesure de la résistance thermique de contact dans les conditions de fabrication d'enrobé bitumineux

Les températures de fabrication des enrobés bitumineux ont une importance capitale pour garantir un bon collage bitume-granulat. Cependant l'évaluation précise de la qualité de collage reste un vrai challenge. Cette étude présente une méthode thermique d'évaluation de la qualité du collage à par la mesure de la résistance de contact à l'interface bitume-granulat. Grâce à un appareil original de mesure, et par résolution numérique du problème de conduction dans le bitume et granulat, on détermine la résistance thermique de contact qui est interprétée comme indicateur de la qualité du collage

Ex vivo activity of the ACT new components pyronaridine and piperaquine in comparison with conventional ACT drugs against isolates of Plasmodium falciparum

<p>Abstract</p> <p>Background</p> <p>The aim of the present work was to assess i) <it>ex vivo </it>activity of pyronaridine (PND) and piperaquine (PPQ), as new components of artemisinin-based combination therapy (ACT), to define susceptibility baseline, ii) their activities compared to other partner drugs, namely monodesethylamodiaquine (MDAQ), lumefantrine (LMF), mefloquine (MQ), artesunate (AS) and dihydroartemisinin (DHA) against 181 <it>Plasmodium falciparum </it>isolates from African countries, India and Thailand, and iii) <it>in vitro </it>cross-resistance with other quinoline drugs, chloroquine (CQ) or quinine (QN).</p> <p>Methods</p> <p>The susceptibility of the 181 <it>P. falciparum </it>isolates to the nine anti-malarial drugs was assessed using the standard 42-hours ³H-hypoxanthine uptake inhibition method.</p> <p>Results</p> <p>The IC₅₀values for PND ranged from 0.55 to 80.0 nM (geometric mean = 19.9 nM) and from 11.8 to 217.3 nM for PPQ (geometric mean = 66.8 nM). A significant positive correlation was shown between responses to PPQ and PND responses (<it>rho </it>= 0.46) and between PPQ and MDAQ (<it>rho </it>= 0.30). No significant correlation was shown between PPQ IC₅₀and responses to other anti-malarial drugs. A significant positive correlation was shown between responses to PND and MDAQ (<it>rho </it>= 0.37), PND and LMF (<it>rho </it>= 0.28), PND and QN (<it>rho </it>= 0.24), PND and AS (<it>rho </it>= 0.19), PND and DHA (<it>rho </it>= 0.18) and PND and CQ (<it>rho </it>= 0.16). All these coefficients of correlation are too low to suggest cross-resistance between PPQ or PND and the other drugs.</p> <p>Conclusions</p> <p>In this study, the excellent anti-malarial activity of PPQ and PND was confirmed. The absence of cross-resistance with quinolines and artemisinin derivatives is consistent with the efficacy of the combinations of PPQ and DHA or PND and AS in areas where parasites are resistant to conventional anti-malarial drugs.</p

The ER-Bound RING Finger Protein 5 (RNF5/RMA1) Causes Degenerative Myopathy in Transgenic Mice and Is Deregulated in Inclusion Body Myositis

Growing evidence supports the importance of ubiquitin ligases in the pathogenesis of muscular disorders, although underlying mechanisms remain largely elusive. Here we show that the expression of RNF5 (aka RMA1), an ER-anchored RING finger E3 ligase implicated in muscle organization and in recognition and processing of malfolded proteins, is elevated and mislocalized to cytoplasmic aggregates in biopsies from patients suffering from sporadic-Inclusion Body Myositis (sIBM). Consistent with these findings, an animal model for hereditary IBM (hIBM), but not their control littermates, revealed deregulated expression of RNF5. Further studies for the role of RNF5 in the pathogenesis of s-IBM and more generally in muscle physiology were performed using RNF5 transgenic and KO animals. Transgenic mice carrying inducible expression of RNF5, under control of β-actin or muscle specific promoter, exhibit an early onset of muscle wasting, muscle degeneration and extensive fiber regeneration. Prolonged expression of RNF5 in the muscle also results in the formation of fibers containing congophilic material, blue-rimmed vacuoles and inclusion bodies. These phenotypes were associated with altered expression and activity of ER chaperones, characteristic of myodegenerative diseases such as s-IBM. Conversely, muscle regeneration and induction of ER stress markers were delayed in RNF5 KO mice subjected to cardiotoxin treatment. While supporting a role for RNF5 Tg mice as model for s-IBM, our study also establishes the importance of RNF5 in muscle physiology and its deregulation in ER stress associated muscular disorders

Étude des transferts thermiques lors de la cristallisation d'un polymère semi-cristallin

L'objectif de cette thèse est d'analyser le couplage entre les transferts thermiques et la cinétique de cristallisation lors de la solidification d'un polymère semi-cristallin, le polypropylène. Nous avons choisi d'effectuer cette analyse pour différents domaines de vitesse de refroidissement. Tout d'abord, nous considérons des vitesses modérées comparables à celles qui prévalent dans l'appareil de caractérisation des cinétiques de cristallisation (DSC). Nous abordons ensuite le cas de vitesses importantes qui sont celles du procédé d'injection où le polymère chaud est mis en contact brusque avec le moule froid. Après avoir brièvement décrit les polymères, leur procédé de mise en forme et les cinétiques de cristallisation, nous présentons les limites de la caractérisation de la cinétique par DSC. Le deuxième chapitre s'applique à la mise en oeuvre expérimentale et à la modélisation du couplage des transferts thermiques avec une cinétique de cristallisation pour les deux configurations que nous avons retenues dans lesquelles les transferts de chaleur sont 1-D...NANTES-BU Sciences (441092104) / SudocNANTES-Ecole Centrale (441092306) / SudocSudocFranceF

Caractérisation et simulation des processus de transferts lors d'injection de résine pour le procédé RTM

NANTES-BU Sciences (441092104) / SudocSudocFranceF

Optimisation thermique du procédé Resin Transfer Molding

Les matériaux composites structuraux, à renfort continus (fibres longues ou tissés) sont de plus en plus utilisés, notamment dans les secteurs automobiles, aéronautiques, nautiques et sportifs. Le procédé Resin Transfer Molding est un procédé de fabrication de pièces composites adapté aux séries moyennes correspondant de plus en plus à celles rencontrées dans l'automobile. Ce procédé répond en outre aux exigences environnementales de non émission de solvant, le moulage étant réalisé en moule fermé. Cette étude réalisée dans le cadre des Programmes de Recherche et d'Innovation dans les Transports Terrestres (PREDIT) du Ministère de l'éducation nationale associait plusieurs partenaires académiques et industriels. Elle s'est intéressée à la caractérisation thermique des matériaux composites à base de polyester insaturé et de renforts en verre, ainsi qu'à leur transformation. On a ainsi effectué l'analyse expérimentale par mesure in-situ et la modélisation des transferts thermiques dans le procédé. Des modèles nouveaux ont été développés et validés. Une première illustration d'une méthodologie d'optimisation thermique du procédé a été montrée.Structural composite materials manufactured with continuous reinforcement (either woven or long fibers) are more and more used, notably in the car industries, aeronautical, nautical and sports domains. The Resin Transfer Molding process is a process of composite part manufacture adapted to average production corresponding more and more to those met in car industries. Besides, this process complies with the environmental requirements of solvent release, molding being achieved in closed mold. This work achieved within the framework of the Programs of Research and Innovation in Ground Transport (PREDIT) of the Ministry of National Education associated several academic and industrial partners. It concerned the thermal characterization of composite materials made of unsaturated polyester and glass reinforcements, as well as their transformation. Experimental analyses were carried out by in-situ measures as well as the modelling of the heat transfer in the process. Some new models have been developed and have been validated. A first illustration of a methodology of thermal optimization of the process has been shown.NANTES-BU Sciences (441092104) / SudocSudocFranceF

TRANSFERTS THERMIQUES DANS LE PROCEDE D'INJECTION BMC (BULK MOLDING COMPOUND)

NANTES-Ecole Centrale (441092306) / SudocNANTES-BU Sciences (441092104) / SudocSudocFranceF